Tractors (This article is taken from the August
1979 Power Farming Magazine, it is not intended for commercial purposes)
A CHAMPION FOR THE
TWO WHEEL DRIVE
While tractor makers around the world
have turned to four-wheel drive to utilize the engine power available in
today's large agricultural tractors, a young enthusiastic engineer and tractor
maker in Australia crusades strongly for the two-wheel drive configuration.
Carl Upton, of Upton’s Engineering, a country manufacturing outfit in
southern NSW, is a delightful young man with a strong passion In life —
building farm tractors which are heavier and better than any he knows. And
even more importantly, to demonstrate a principle he has long espoused in
tractor design. He believes, up to a point, two-wheel drive traction will
do everything and more than four-wheel drive. The point is up to 350
horsepower! But what you really have to like about Carl Upton is that he is
prepared to put his money where his mouth is. Further, he is also prepared to
lake his giant tractors to major field days and "take on" the big
four-wheel drives, Pulling some or the giant rigs on demonstration.
Some of the major makers look askance when Carl, Undeterred, backs up to a
huge machine that has some of the biggest 4-wds scratching to pull them. In
turn, heads are scratched when he walks away with the load.
What's the secret? Carl says there is none. It's just a matter of weight —
plenty of it in the right place — and lyres big enough to accept the load at
reasonable wheel slip performance.Well, if it's weight you need. the
tractors built by Carl Upton are not lacking. How docs an operating weight in
excess of 23-000 kg (51 000 Ib) for a two-wheel drive tractor sound?
Admittedly, we are talking about a 350 hp tractor (gross engine) but that's
considerably more weight than found in many of the big four-wheel drives.
Carl Upton has been custom building big tractors for some years and is adamant
that four-drive wheels arc not needed for tractors under 350 horsepower.
Many tractor men would argue about that and are skeptical about Carl's
philosophy and his claims that he can build tractors up to 350 engine
horsepower that have lower wheel slip than 4-wds and consequently higher
drawbar efficiency. ,
You may ask — how does he achieve such massive weight? If we take a brief
look at the biggest Upton unit yet built — the HT 14/350 (14 fwd gears 350
hp) the weight of material used in the back end is nothing short of
staggering.The rear halt of the chassis is constructed from 4 in. thick
plate and the bare chassis weight is 6 tonnes, with main front chassis members
constructed from 15 x 6 x 1/1/2 channel.
Another example of the massive weight and strength built into the Upton
machine is the 350 gal fuel tank which has a floor made from 2-3/8 in. plate
with the balance of the construction utilizing 1 in. plate. Weight of the fuel
tank empty is 3 tonnes.
The eye-opener drawbar needs special mention, as I doubt if there is a more
massive similar component on any (arm tractor in the world It weighs about 680
kg (1 500 Ib) and is made from 6 x 4 in. plate and is contained within a 4 in.
plate frame. And just for the record, the pull is taken on a 3 in. diameter
hardened steel pin!
With existing agricultural tires being too small to meet the traction demands
of two drive wheels only, Carl Upton turned to earthmover tires and is more
than happy with the result. The HT 14/350 is equipped with 33.5 x 33 x 20 ply
tires which have a circumference 20% greater than the 30.5 x 32 agricultural
tires commonly used on big tour-wheel drives.
Carl is satisfied that the earthmovers have more than lived up to his
expectations, providing u high efficiency of traction with adequate flexing
for agricultural work during extreme drawbar pulls.
In more philosophical' detail, Upton claims that any 2-wd tractor should carry
most of its weight on the rear drive wheels. The Upton tractor puts this
into effect with static weight of 20% on the front and 80% on the rear and the
long (3.9 m) wheelbase helps stabilize weight transfer and provides a smooth
In fact, when the tractor is under load, dynamic weight on the drive wheels
can be as high as 88% of the total vehicle weight.
Although overall, of rigid frame design, the tractor frame is built in two
sections of the dimensions referred to earlier. The rear portion of the frame
as can be seen in the photographs is of massive box construction to resist
distortion in any direction.
The drive axle has a capacity of 29 545 kg (65 000 lb) and the planetary
gearing incorporates guided needle rollers and nitrided gearing. Reduction
ratio is 4.32:1.
The driving head assembly is an Eaton 23121 series with a 6.17:1 ratio.
Overall ratio is 26.65:1.
The axle is wholly of Australian design and manufacture, excepting the Eaton
The only tires offered, as mentioned, are 33.5 x 33 20 ply E-2 earthmover
singles. Because of the weight, width and tangential pull limitations, any
smaller tire dualled would be overloaded, says Carl.
Adequate flotation is provided by a large ground contact area of 5 907 sq cm
(900 sq in.) per tire.
Operators are well protected from the elements by the cab which is of module
design located on four rubber mounts and is a self contained unit.
Whatever conjecture there may be about Carl Upton's philosophy on 2-wd v 4-wd,
it would be hard to find a critic of the finish of his product. In particular,
the cabin and cabin layout is exceptional in concept and comfort. The cabin,
one of the biggest in the game, probably the biggest, is designed for function
and comfort down to the last detail.
Electrical connections are handled by bulkhead connectors on the firewall.
All other controls are cable operated so no solid metal shafts can transfer
noise and vibration and cause dust sealing problems-Gauge instrumentation
includes a temperature gauge, oil pressure gauge, ammeter, tachometer, hour
meter and exhaust pyrometer and turbo-charger boost pressure gauge.
Indicator lights monitor engine oil temperature, transmission level, low air
pressure, tow water level and the park brake operation. In addition, a Micro
guard engine protection system operates on the engine water temperature,
engine block water pressure and engine oil pressure.
An exclusive feature of the cab control layout is the method of mounting the
throttle, pneumatic gear shift valve and the parking brake valve on the side
of the swiveling seat. This permits the operator to control tractor speed and
gear changes regardless of the direction he is facing inside the cab.
Also, by grouping the controls in this way, the tractor can be driven
through the gears similar to a road transport, when operating on the road,
pulling large four-wheeled trailers.
Among other standard cab features are air conditioning, stereo radio, interior
light, two speed windshield wiper and washer, a soft feel steering wheel, and
A fail-safe airbrake system has been included to ensure the vehicle has
excellent braking performance. This system has proven to be extremely safe,
reliable, and virtually maintenance free.
The 514 mm x 178 mm drum brakes are operated by Westinghouse spring brake
chambers. If for any reason air pressure is lost, the brakes will
automatically be applied.
However, if this should happen, the brakes can still be operated by an
emergency over-ride system. All the brake system components are common to the
transport industry, with service and spare parts readily available
throughout the country.
The tractor is powered by a turbocharged and after-cooled Cummins 6-cyl
diesel engine which produces 261 kW (350 hp) at 2100 rpm. Maximum torque is 1
365 Nm (1 006 lb ft) at I 500 rpm with a torque rise of 15% .
Driveline components include a Spicer two-plate 15-1/2in. clutch, a Spicer
SST-14 transmission and Spicer 1710 series universal joints.
Performance-wise, Upton claims that field tests have indicated that the HT
14/350 can produce a sustained pull in excess of 90 kN (20 000 lb) without
water ballast in the rear tires. With the tractor fully ballasted, a drawbar
pull of 133 kN could be realized it is claimed.
It is also said that despite its high engine power for a 2-wd configuration,
the engine can be full loaded in the field at speeds as low as 6.4 km/h. The
low speed lugging ability can be attributed to the high weight to horsepower
ratio of 147 Ib/hp. The adjustable height drawbar (through 24 in.) fully
utilizes weight transfer and provides increased traction under load.
Carl Upton rightfully claims that the HT 14/350 must surely be one of the
world's most unique farm tractors.
And in talking to him, he frequently gets back to the theme that the ability
of the tractors he builds to transmit full engine power through two driving
tires must surely place a big question mark on the need for four-wheel drive
tractors in the high horsepower range as used in large scale farming
The Upton HT14/350 pulling 60 ft of blade
plough on demonstration at one of Australia's largest field day exhibitions.
Incidentally, the different looking blade plough you see is made in Australia by